State of emergency for planet earth

• weka
• 7 years ago
• Categories: climate change, disaster, Environment, science
• Tags: james hansen, the long emergency

There’s a current state of emergency happening in Dunedin, Otago, Waitaki and Canterbury due to heavy rainfall and flooding. Wishing everyone affected all the best.

That’s the short emergency. Here’s the long one. James Hansen and a team of climate scientists just published this,

Abstract. Global temperature is a fundamental climate metric highly correlated with sea level, which implies that keeping shorelines near their present location requires keeping global temperature within or close to its preindustrial Holocene range. However, global temperature excluding short-term variability now exceeds +1 °C relative to the 1880–1920 mean and annual 2016 global temperature was almost +1.3 °C. We show that global temperature has risen well out of the Holocene range and Earth is now as warm as it was during the prior (Eemian) interglacial period, when sea level reached 6–9 m higher than today.

Further, Earth is out of energy balance with present atmospheric composition, implying that more warming is in the pipeline, and we show that the growth rate of greenhouse gas climate forcing has accelerated markedly in the past decade. The rapidity of ice sheet and sea level response to global temperature is difficult to predict, but is dependent on the magnitude of warming. Targets for limiting global warming thus, at minimum, should aim to avoid leaving global temperature at Eemian or higher levels for centuries. Such targets now require negative emissions, i.e., extraction of CO₂ from the air.

If phasedown of fossil fuel emissions begins soon, improved agricultural and forestry practices, including reforestation and steps to improve soil fertility and increase its carbon content, may provide much of the necessary CO₂ extraction. In that case, the magnitude and duration of global temperature excursion above the natural range of the current interglacial (Holocene) could be limited and irreversible climate impacts could be minimized.

In contrast, continued high fossil fuel emissions today place a burden on young people to undertake massive technological CO₂ extraction if they are to limit climate change and its consequences. Proposed methods of extraction such as bioenergy with carbon capture and storage (BECCS) or air capture of CO₂ have minimal estimated costs of USD 89–535 trillion this century and also have large risks and uncertain feasibility. Continued high fossil fuel emissions unarguably sentences young people to either a massive, implausible cleanup or growing deleterious climate impacts or both.

…

Our conclusion that the world has overshot appropriate targets is sufficiently grim to compel us to point out that pathways to rapid emission reductions are feasible.

My translation of that reserved science speak:

1. we’ve missed the agreed targets that would allow BAU for Western civilisation
2. the only thing to do now is drop fossil fuels rapidly
3. high tech Carbon Capture and Storage (CCS) is very expensive, unreliable, risky, and probably implausible as a solution.
4. low tech sequestration via natural cycles might buy us some time but on its own won’t be enough
5. it’s our kids that will bear the brunt of this

I’ll add,

1. saving the conventional economy can no longer be the priority. We have to drop fossil fuel use immediately.
2. the Powerdown gives us the best shot at this without collapse.

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Moderator note: zero tolerance of climate change denial or ‘we’re all going to die, it’s too late’ comments.